Magnetic shield for charged particles

ABSTRACT

A magnetic field and charged particle shield comprised of a plurality of permanently magnetized elements. In one embodiment, each element resembles a truncated pyramid with the pyramid base representing one pole and the top of the other pole and the elements are connected together to form a cube in which one or more sides may be missing to provide a guide for deflected particles. Each element preferably has a lip along one edge thereof so that the structure has either a male extension or female depression on each of its sides which mates with a depression or extension of another structure so that a wall can be constructed using such structures as building blocks. In a further embodiment, two extending flexible sheets having opposing surfaces of different magnetic polarity are connected together so that a surface of each is substantially parallel and adjacent surfaces have the same polarity.

United States Patent [191 Grosbard MAGNETIC SHIELD FOR CHARGED PARTICLES [76] Inventor: Gregory Grosbard, 353 W. 19th St.,

New York, NY. 10011 [22] Filed: Nov. 3, 1971 [21] Appl. No.: 195,340

[52] US. Cl 250/515, 174/35 R, 250/517, 250/519 [51] Int. Cl. G2lf 3/00 [58] Field of Search... 250/108 R, 108 WS, 108 FS; 174/35 R, 35 MS [56] References Cited UNITED STATES PATENTS 3,233,950 2/1966 Baermann 308/10 2,720,105 10/1955 Billups 250/108 WS X 2,847,581 8/1958 Clark 250/108 R 2,932,745 4/1960 Alberti et a1 i. 250/108 WS 3,065,351 11/1962 Weinberger et a1 250/108 FS 3,164,840 1/1965 Reynolds 250/108 PS X 3,320,455 5/1967 Whetten et a1. 250/108 R X Mar. 26, 1974 Primary Examiner-Archie R. Borchelt Attorney, Agent, or Firm-Clarence A. OBrien; Harvey B. Jacobson 1 71 ABSTRACT A magnetic field and charged particle shield comprised of a plurality of permanently magnetized elements. In one embodiment, each element resembles a truncated pyramid with the pyramid base representing one pole and the top of the other pole and the ele ments are connected together to form a cube in which one or more sides may be missing to provide a guide for deflected particles. Each element preferably has a lip along one edge thereof so that the structure has either a male extension or female depression on each of its sides which mates with a depression or extension of another structure so that a wall can be constructed using such structures as building blocks. In a further embodiment, two extending flexible sheets having opposing surfaces of different magnetic polarity are connected together so that a surface of each is substantially parallel and adjacent surfaces have the same polarity.

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5mm 3 {IF 5 INVENTOR $62-$02) 7easamev ATTORNEYS dwww f 41440 l MAGNETIC SHIELD FOR CHARGED PARTICLES BRIEF DESCRIPTION OF THE PRIOR ART AND SUMMARY OF THE INVENTION The invention relates to a magnetic shield for magnetic fields and charged particles.

Magnetic fields can be attenuated in strength by magnetic shields now in use, such as thick metal plates, but connot be totally blocked. While the almost total attenuation which can be obtained is satisfactory for almost all applications, there are a few instances in which total blocking is necessary, such as, for example, to form the walls of a room where vital computer tape or similar records are stored or which must be secured against electronic eavesdropping. Further, there are many applications where it is desirable to block the passage of charged particles, such as X-rays and the like with a shield, which may also serve to attenuate stray magnetic fields.

The present invention relates to a magnetic shield which totally blocks magnetic fields and also operates to deflect the path of charged particles passing through the shield. Not only is the shield useful in those applications where total blocking is required, but its simplicity and effectiveness make it a practical alternative to shields now in use for attenuating fields. In the embodiment of the invention described below, the novel shield of this invention comprises a plurality of magnetic elements each having one pole face at one location and the other pole face at another location. The elements are connected together so that all of one of the poles are located adjacent each other in the interior of the resulting structure and all of the other one of the poles are on the exterior surface of the resulting structure. The interaction of the fields produced by the elements blocks the penetration of external fields through the shield and also deflects charged particles which enter the shield.

Accordingly, in a further embodiment of this invention, each of the elements has a portion shaped like a truncated pyramid so that four, five or six of the elements can be combined to form a cubically shaped structure having an interior cavity and, with four or five elements, has one or two open sides connecting the interior cavity to the exterior of the structure. The elements each preferably have a lip portion so that when combined the structure has either female depressions or male extensions on each of the cube sides with the lips also serving to block the magnetic flux leaking out of the structure. Female and male structures can then be used as building blocks to form a wall or the like. When less than six cubes are employed in each structure, the resulting air spaces between the interior and exterior of the cubical structure act as guides for charged particles which enter and are deflected within the structure.

According to another embodiment, two extending sheets of magnetic material, each having one extending surface of one polarity and an opposing extending surface of the other, are connected together with a surface of each of the same polarity held adjacent so that the resulting structure deflects charged particles, which I penetrate either of the sheets, along a direction substantially parallel to the sheet surfaces. The sheets can be formed as an apron to be worn for protection against X-rays or similar radiation and a strip of similar material can be disposed around the ends of the other sheets to close the space between the other sheets.

Many other objects and purposes of the invention will become clear from the following detailed description of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I shows a perspective view of a female structure;

FIG. 2 shows a cutaway view of the structure of FIG. 1 along the lines 2-2';

FIG. 3 shows a perspective view of one of the elements of the structure of FIG. 1;

FIG. 4 shows a top plan view of the element of FIG.

FIG. 5 shows a bottom perspective view of the element of FIG. 3;

FIG. 6 shows a top view of another of the elements of the structure of FIG. 1;

FIG. 7 shows a cutaway view of the element of FIG. 6 along the lines 7-7;

FIG. 8 shows a perspective view of the element of FIG. 6;

FIG. 9 shows a perspective view of a male structure;

FIG. 10 shows a cutaway view of the structure of FIG. 9 along the lines 10-10;

FIG. 11 shows a perspective view of one of the elements of FIG. 9;

FIG. 12 shows a bottom perspective view of the element of FIG. 11;

FIG. 13 shows a cutaway view of another of the ele ments of FIG. 9;

FIG. 14 shows a cutaway view of another male structure having no central cavity;

FIG. 15 shows a perspective view of another structure;

FIG. 16 shows an apron of this invention;

FIG. 17 shows a cutaway view of the apron of FIG. 16 along the lines 17l7; and

FIG. 18 shows a cutaway view of another apron;

FIG. 19 shows a wall assembled from male and female elements.

DETAILED DESCRIPTION OF THE DRAWINGS Reference is now made to FIGS. 1 and 2 which show a perspective view of a combined female structure 20 and a cutaway view of structure 20 along the lines 2-2. Structure 20 is comprised of six elements each formed in part as a pyramid so that, when combined, the resulting structure is cubical. Elements 22, 24, 26, 28 and 30 can be seen in FIGS. 1 and 2. These elements can be held together by any suitable means, for example by seam welding along exterior surface portions where the elements meet.

Each element is permanently magnetized with one exterior surface having one magnetic polarity and an interior surface having the opposite polarity. Surface 32 including the contacting interface portions 33 of e1- ement 22, shown in perspective in FIG. 3, has one polarity and surface 34 the opposite. The elements in combined structure 20 are disposed so that the same poles of all the elements are adjacent and confront each other within the interior of structure 20 and the other poles of the elements form a continuous exterior surface of structure 20. Thus, the interaction of the magnetic fields produced by the elements which comprise structure 20 is internally confined with minimal flux leakage to prevent penetration through structure 20 of any stray magnetic field having a strength which is less than the strength of the fields within structure 20.

Further, each of the elements comprising structure 20 has a flux leakage blocking lip portion so that, when the elements are put together, female structure 20 has a female depression on each of its six sides into which a male extension on the side of a similar male structure can fit. Element 22, shown in FIGS. 3, 4 and 5, has a lip 40 which extends along one lower edge of the truncated pyramid which forms part of element 22 from a point near the intersection of that edge with another lower edge to another point near the intersection of that edge with a third lower edge. Elements 24, 26 and 28 are the same shape as element 22 so that, when fitted together as shown in FIGS. 1 and 2, the lips form two parallel raised surfaces running along two edges of each of the four sides thus formed.

Element 30, as well as the sixth element which cannot be seen in FIGS. 1 and 2, is formed differently from elements 22, 24, 26 and 28. As can be seen in FIGS. 6-8, element 30 has a raised lip 42 which runs entirely around its lower edges. Lip 42, and the lip on the sixth element which is the same as element 30 form part of a raised area which binds central depressions 34, 46, 48 and 50. Element 30 similarly has a central depression 52 as does the sixth element not shown.

Structure 20 is thus a female structure which has female depressions in each of its six sides which each can receive one of a number of male extensions on a male structure which has male extensions on each of its six sides. FIGS. 9 and illustrate a male structure 54 which is comprised of elements 60, 62, 64, 66, 68 and a sixth element which is identical to element 60 but which cannot be seen in FIGS. 9 and 10.

Element 62, which is shown in FIGS. 11 and 12 and which is identical to elements 64, 66 and 68, has a raised male extension 70 and a lip 72 which is raised to a height less than the height of extension 70 so that, when elements 62, 64, 66 and 68 are fitted together as shown in FIGS. 9 and 10, the male extension on each element extends so as to fit into a female depression in a female structure such as shown in FIG. 1. Element 60, shown in FIG. 13 in cross section is identical to element 30 shown in FIGS. 6-8 with a lip 74 about its lower edges, except that element 60 has a male extension 76 instead of a female depression. Accordingly, when the six elements comprising structure 54 are assembled, structure 54 has a male extension on each of its six sides, each of which can fit into one of six female depressions on a female structure such as structure 20.

The element from which structures 20 and 54 are assembled may be made from any material capable of being permanently magnetized. Such materials and their properties, including magnetic coercise force or strength are well known. Barium ferrite in a magnetic powder mixture held together in a plastic binder is re,- ferred to as such a material by way of example, in U. S. Pat. No. 3,233,950 to Baermann. The specific composition and strength of the magnetic material utilized is not critical to this invention and forms no part thereof.

A number of female structures, such as structure 20, and male structures, such as structure 54, can be easily fitted together to form a wall 80 or the like as shown in FIG. 19. Other similar walls, ceilings and floors could be used to make a room, the interior of which is fully protected against stray magnetic fields and charged particles, such as X-rays.

In structures and 54, the elements which comprise each structure are shaped in part like a truncated pyramid with element 30, for example, having a flat surface 32 which represents one pole face and the other elements having similar surfaces. Thus, when assembled, structures 20 and 54 have central cubical cav ities which may in some instances be desirable. How ever, such a cavity is not necessary and may be undesirable in some circumstances. Accordingly, FIG. 14 shows a structure 86 which is identical to structure 54 except that there is no central cavity.

Further, it may be desirable for some applications not to completely close the structure but instead to provide an air passage between the interior location where the poles of the elements are located and the exterior of the structure. Preferably this passage extends substantially transverse to the direction from which the charged particles which are to be deflected enter. The particles are thus guided out of the structure along the passageway. FIG. 15 shows a cubical structure 90 comprising at least four elements, including elements 92 and 94, such as discussed above. However, no element is disposed in region or passage 96 so that this passage guides charged particles which enter the structure via one of the elements out of it as the particles are deflected by the magnetic fields produced by the elements comprising structure 90.

The elements which comprise the above structures can be made of any suitable material capable of being permanently magnitized as aforementioned, such as a magnetically oriented ceramic. Many such materials are available. Alternatively, the elements may be made from flexible material such as rubber as the binder aforementioned into which magnetic particles have been dispersed while the material is soft or molten. A magnetic field is then applied to orient the particles so that when the material is soft, the particles cannot thereafter migrate or move and the material is permanently magnetically oriented.

FIGS. 16 and 17 illustrate a further embodiment of the invention in which the magnetic shield includes two flexible extending sheets each having a first extending surface representing one pole face and an opposing extending surface representing the other pole face. The material may be the flexible material described above. The two sheets are connected together so that a surface of each extends adjacent and substantially parallel to a surface of the other and the adjacent surfaces have the same polarity and repel each other. Thus, charged particles which enter the structure which includes these two sheets are deflected.

FIGS. 16 and 17 in particular show an apron 100 which is also provided with strings 102 and 104 which can be looped about the neck and chest respectively for holding the apron in position on humans of varying size. Apron 100 includes sheets 106 and 108 which are held together by any suitable means, such as hooks 110, so that the surfaces of sheets 106 and 108 having the same pole face are adjacent as shown.

If desired a similar strip of material 112 having one extending surface representing one polarity and an opposing surface representing the opposite polarity can be disposed around the edge of apron 100 to enclose the space between sheets 106 and 108. Strip 112 is preferably held so that the surface of strip 112 which faces the interior space between sheets 106 and 108 is of the same polarity as the surfaces of sheets 106 and 108 which are adjacent. Strip 112 can be held in place by any suitable means, e.g., welding or glue. The strip may be omitted as shown in FIG. 18 where sheets 120 and 122 are held together by hooks 124 without anything closing the space between sheets 106 and 108.

Charged particles, which enter one sheet are deflected by the magnetic fields produced by sheets 106 and 108 and move parallel to the surfaces of sheets 106 and 108 and pass harmlessly out of the apron. Thus, a person wearing the apron is fully protected against radiation of charged particles.

Many changes and modifications in the above embodiments can of course be made without departing from the scope of the invention. Accordingly, that scope is intended to be limited by the scope of the appended claims.

What is claimed is:

I. In a magnetic shield, a plurality of separately magnetized bodies having exterior pole surfaces only of one and the same polarity and interior pole surfaces only of opposite polarity to said exterior surfaces, and means securing said magnetized bodies to each other with the interior surfaces in confronting relation for preventing establishment of external flux paths between the exterior and interior surfaces.

2. The combination of claim 1 wherein said interior surfaces of the magnetized bodies include contacting portions extending outwardly toward said exterior surfaces and edge portions between the interior and exterior surfaces, and means connected to the exterior surfaces enclosing said edge portions for blocking magnetic flux leakage.

3. The combination of claim 2 wherein said exterior surfaces of the respective bodies are perpendicular to lines of flux emitted therefrom when disassembled from each other.

4. The combination of claim 1 wherein said exterior surfaces of the respective bodies are perpendicular to lines of flux emitted therefrom when disassembled from each other.

5. The combination of claim 1 wherein the shield enlcoses an internal cavity bounded by said interior surfaces of the magnetized bodies.

6. The combination of claim 2 wherein the magnetized bodies are seam welded to each other along the edge portions.

7. The combination of claim 1 wherein said exterior surfaces of the magnetic bodies are substantially parallel to each other.

8. The combination of claim 7 wherein the interior surface of each of the magnetized bodies forms a crosssectional perimeter in a plane parallel to the exterior surface of decreasing length in a direction perpendicular to said plane.

9. The combination of claim 8 wherein exterior surfaces of the magnetized bodies enclose a cubical volume to form a shielding unit.

10. The combination of claim 9 wherein exterior surfaces of adjacent shielding units in contact with each other have interfitting projections and recesses.

11. The combination of claim 1 wherein exterior surface of the magnetized bodies enclose a cubical volume to form a shielding unit.

12. The combination of claim 11 wherein exterior surfaces of adjacent shielding units in contact with each other have interfitting projections and recesses. 

1. In a magnetic shield, a plurality of separately magnetized bodies having exterior pole surfaces only of one and the same polarity and interior pole surfaces only of Opposite polarity to said exterior surfaces, and means securing said magnetized bodies to each other with the interior surfaces in confronting relation for preventing establishment of external flux paths between the exterior and interior surfaces.
 2. The combination of claim 1 wherein said interior surfaces of the magnetized bodies include contacting portions extending outwardly toward said exterior surfaces and edge portions between the interior and exterior surfaces, and means connected to the exterior surfaces enclosing said edge portions for blocking magnetic flux leakage.
 3. The combination of claim 2 wherein said exterior surfaces of the respective bodies are perpendicular to lines of flux emitted therefrom when disassembled from each other.
 4. The combination of claim 1 wherein said exterior surfaces of the respective bodies are perpendicular to lines of flux emitted therefrom when disassembled from each other.
 5. The combination of claim 1 wherein the shield enlcoses an internal cavity bounded by said interior surfaces of the magnetized bodies.
 6. The combination of claim 2 wherein the magnetized bodies are seam welded to each other along the edge portions.
 7. The combination of claim 1 wherein said exterior surfaces of the magnetic bodies are substantially parallel to each other.
 8. The combination of claim 7 wherein the interior surface of each of the magnetized bodies forms a cross-sectional perimeter in a plane parallel to the exterior surface of decreasing length in a direction perpendicular to said plane.
 9. The combination of claim 8 wherein exterior surfaces of the magnetized bodies enclose a cubical volume to form a shielding unit.
 10. The combination of claim 9 wherein exterior surfaces of adjacent shielding units in contact with each other have interfitting projections and recesses.
 11. The combination of claim 1 wherein exterior surface of the magnetized bodies enclose a cubical volume to form a shielding unit.
 12. The combination of claim 11 wherein exterior surfaces of adjacent shielding units in contact with each other have interfitting projections and recesses. 